Could Cannabis Be The Cause For Depression?

I was diagnosed with cannabis induced psychosis by my psychiatrist. I strongly disagree that cannabis caused my illness and told my dr several times that I had depression and social problems long before using cannabis. As a matter of fact my use brought me out of my shyness and treated my depression. Why is this doctor making "assumptions" that this herb caused my mental problems? I've been clean for over 3 years now and she still has this diagnosis listed. What is wrong with our mental health treatment in this country??